Echinococcosis poses a serious threat to human health. The major objective of this project is to obtain basic information that will lead toward a better understanding of the biologic nature of the etiological agents of this disease which is necessary for the development of effective methods for its treatment and eventual control. Accordingly, an in vitro system developed in this laboratory for the axenic cultivation of tapeworms will be utilized in studies: 1. to compare growth, morphology, and rates of a sexual reproduction in the larval stages of three species of taeniid cestodes, namely Echinococcus granulosus, Echinococcus multilocularis and Taenia crassiceps when reared under identical conditions in vitro; 2. to compare mitotic activity in the larval stages of these taeniid cestodes which exhibit three different processes of a sexual reproduction; and 3. to analyze and compare certain aspects of carbohydrate metabolism by these species at different intervals of time during the process of a sexual reproduction in vitro.